Lithium ion (Li-ion) batteries are widely used from portable electric devices to electric cars. In these batteries, Li-ions intercalate primarily the anode material before discharge. During discharge they migrate from the anode through the electrolyte into the cathode, where they intercalate the cathode material. While Li-ions migrate from one electrode to the other, they change the oxidation number of the atoms in the electrodes they migrate from/to, as simultaneously with Li-ion migration, also electrons migrate from the anode to the cathode during discharge. Through these processes an electric circuit is operated with current flowing from the anode to the cathode in the electrolyte and from the cathode to the anode via the wire and load connecting the electrodes, during discharge. The driving force of the process is the chemical potential difference between the electrodes. Batteries operate until this potential difference fails to exist. During recharging this potential difference will be restored by an external power source.
Several intercalation materials are used as electrode components. Typically the anode (of the discharge) is made of graphite intercalating Li, the cathode (of the discharge) is made of transition metal compound (LiFePO4, LiCoO2, LiMn2O4, etc) nanocrystals embedded into a carbon matrix, the electrolyte is a non-aqueous liquid or polymer, and a membrane separates the anode and cathode spaces allowing for the passage of Li-ions only.
The performance of Li-ion batteries depends on the choice of the intercalation materials in the electrodes, and on the other components of the battery. Batteries that intercalate other than Li-ions are also known, for example in K-ion batteries (A. Eftekhari (2004), “Potassium Secondary Cell Based on Prussian Blue Cathode”, Journal of Power Sources 126, 221) metal-organic frameworks do the intercalation in the cathodes during the discharge.
The use of ternary acetylides as Li-ion battery anode materials has been suggested in R. Pöttgen, et al. (2010), “Lithium-Transition Metal-Tetrelides—Structure and Lithium Mobility”, Zeitschrift für Physikalische Chemie 224, 1475, even though only the use of LiAgC2 and LiAuC2 has been explicitly mentioned, as the only structurally characterized Li containing members of ternary acetylides at the time of the publication. LiMC2 compounds would, however, be disadvantageous to be used as anode materials because highly explosive AgC2 and AuC2 would form when these anode materials are fully discharged. Note that the alkalinated transition metal acetylides are not explosive and can survive heating to 500° C. and above, and grinding as reviewed in U. Ruschewitz (2006), “Ternary Alkali Metal Transition Metal Acetylides”, Zeitschrift für Anorg. Allg. Chem., 632, 705.